Vaccination of poultry is a widely used strategy to prevent outbreaks of Marek's disease (MD), infectious bursal disease (IBD), Newcastle disease (ND), infectious bronchitis (IB), avian influenza (AI), and infectious laryngotracheitis (ILT). Live vaccines are currently used to control these diseases. Using live vaccines has the disadvantage of protecting against only a single disease and many live vaccines used in the poultry industry cause a mild form of the disease affecting production yields. Simultaneous protection of poultry against multiple diseases through the use of a single vaccine would be beneficial. In recent years, recombinant avian viral vectors have been used experimentally and commercially to vaccinate poultry against these diseases. The serotype 3 Marek's disease virus herpesvirus of turkey (HVT) is the most commonly used backbone vector in the poultry industry. HVT is also the most commonly used vaccine to control MD. Currently there are HVT-vectored IBD, HVT-vectored ND, HVT-vectored AT, and HVT-vectored ILT vaccines used to control disease in poultry flocks around the world.